Electroacoustic system



R. H. RINESv 2,539,593

ELECTROACOUSTIC SYSTEM Jan. 30, 1951 Filed July 18, 1945 2 Sheets-Sheet 1 MAXIMUM SOUND DIRECTIVITY j MAXIMUM RADIO V mREcnvnY 7\RHDIO FRFG/YCY TRANSMITTER 0R RECEIVER 0R F566/ VER pdb/Q! frega/ fn R. ||.V RINES ELECTROACOUSTIC SYSTEM Jan. 30, 1951 Filed July 18, 1945 2 snets-sneet 2 SOUND E V5 n me #c Or/NQ f fr 2l, 1M

Patented Jan. 30, 1951 UNITED STATES PATENT OFFICE ELECTROACOUSTIC SYSTEM Robert Harvey Rines, Brookline, Mass. Application July 18, 1945, Serial No. 605,722

(Cl. Z50-6) 23 Claims. l

The present invention relates to the transmission and reception of intelligence, using both sound and electromagnetic energy as the agencies of communication, and more particularly to methods and means employing the directive discrimination of sound beams. The term sound will be employed hereinafter, in the specification,

to include the supersonic, as well as the audible,

part of the sound spectrum, and to include also all kinds of elastic vibrations. The invention, indeed, iinds particular application to supersonic communication.

An object of the invention is to provide a new and improved combined-sound-and-electromagnetic system for communication.

A further object is to provide a new and improved system for modulating and demodulating radio waves. l

Another object is to provide a new system for mechanically modulating radio waves. i

Another object of the invention is to provid a new and improved combined-sound-and-radiov system for communication employing a vibratoryv diaphragm of the character described in Letters Patent of the United States 2,063,944, issued December 15, 1936, to George W. Pierce.

A further object is to provide a new and improved system for modulating a radio wave in accordance with a sound wave.

A further object is to provide anew and improved system for secret signaling. K

Other and further objects will be explaine hereinafter and will be particularly pointed out in the appended claims.

The invention will now be more fully explained in connection with the accompanying drawings, in which Fig. 1 is a diagrammatic view of circuits and apparatus embodying the invention; Fig. 2 is a similar View of a modified rotatably adjustable system; Fig. 3 illustrates an omni-directional modication; and Fig. 4 is a perspective view of a further modification embodying an electromagnetic wave guide system, illustrated as of the chanically connected together in the form of two pairs, but insulated from one another. The

diaphragms may be in the form `of plates or rods, or they may be of any other suitable form. The

adjacently disposed boundaries or ends of the diaphragms 1 and 9 are .Shwe connected to YPierce on the said December 15, 1936.

gether rigidly by insulating members I3,- through the medium of rivets II and I5. The adjacently disposed ends of the diaphragms l1 and I9 are shown similarly connected together rigidly by insulating members 23 through the medium of rivets 2l and 25. It is desirable that the insulating members I3 and 23 be constituted of material that shall insulate or isolate not only electrically but also acoustically. As sound or vibration dampers they will prevent sound-vibration interference between the diaphragms 'l and 9 and between the diaphragms I1 and I9, respectively. The connections between the pair of diaphragms I and 9 and the pair of diaphragms l1 and I9 may be of the type described in Letters Patent 2,063,945, also issued Vto the said George W. The greater the number of these diaphragms employed, the more directive will be the system. According to the modication illustrated in Fig. 2, therefore, not only the diaphragms 'I and 9, but also the diaphragms Il and I9, as well as several further diaphragms 2l and 29, are shown connectedY together rigidly by insulating members, diagrammatically indicated at I3. Only two such pairs of diaphragms are shown, for illustrative purposes, however, in Fig. 1.

As described in the said Letters Patent, the said other ends of the diaphragms l, 9, Il and I9 may be respectively provided with units for interconverting vibrational and electric energy. Electric current or voltage may thus be obtained in response to mechanical vibration or pressure, or mechanical vibration or. pressure may be obtained in response toelectric current or voltage. These interconverting unitsmay, as shown, be of the magnetostrictive type, or of any other desired type, such asvpiezoelectric or magnetomotive. Magnetostrictive cores 5, 45, 55 and 35 are shown insulatingly connected at 93 to the said other ends of the respective diaphragms 1, 9, I1

vand I9. These Vcores are respectively associated with pickup coils 3, 53,V 53 and 33, respectively connected to sound transmitters or receivers I, 4I, 5I and 3l. Only a single interconverter 3, 5

a of mechanical and electric energy is shown, however, in the embodiment or Fig. 2. Withinsulating members I3 that isolate electrically only, the

' transverse vibrations ofthe element 29 of Fig. 2,

cooperating with the interconverter 3, 5, may be coupled to the other diaphragm elements as well. The'energy may be amplified, as is also explained in the said Letters Patent.

When the system is used for transmitting elastic vibrations, for example, the transmitters l, 4l, 5l and 3l will excite the respective cores 5, 45, 55 and 35 into magnetostrictive vibration with the result that, at the critical frequency, a sound beam of maximum intensity will be emitted or transmitted from the diaphragm elements 1, 9, I1, I9 for propagation along the direction 6--6 into the sound-conducting medium in which the elements are disposed. This is effected by means of a plane-wave front at right angles to the direction of the beam of signal sound waves, making the Pierce angle 6 with the plane of the diaphragms on which the wave iront is incident.

This angle is determined by the relation V0 sin 0- V where V is the velocity, at the critical frequency, of the propagation of the transverse mechanical sound-wave vibration in the diaphragm, and Vo is the corresponding velocity of propagation in the medium, which here may be the air. In transmission, for example, the sound beam is produced by exciting the diaphragms 1, Si, II and I9 into transverse fundamental or harmonic vibrations that travel along the diaphragms with a velocity having a component, in the direction f as explained in the said Letters Patent, at the critical angle 0, the periodic impulses of pressure of the sound beam al1 strike certain points off the diaphragm in the same phase, say, a push;

' and the rariled impulses similarly all strike other points in phase, say, a pull. Measuring distances" in the direction of propagation of the sound beam in the medium, these alternate high-pressure and low-pressure points are spaced a half-wavelength apart.

It is preferred, as before stated, to employ the signal sound at supersonic frequencies or, at least, at other high frequencies above those of speech.

At the critical angle 0, if the half-wavelength of transverse vibration in the diaphragm is greater than the half-wavelength of the longitudinal waves in the medium, the periodic displacement oaf the parts of the diaphragms will be such that cumulative interaction occurs between the transverse vibrations of the segments of the dia- 1 phragms and the supersonic or super-speech components of vibration of the sound beam, the number of segments being proportional to the frequency. The sound-wave pressure fluctuations in the medium strike all vibratory regions in the diaphragm in the proper phase to enhance the vibration, producing spacial resonance between the diaphragm and the vibrations in the medium. There results an interchange of supersonic or super-speech energy between the medium and the diaphragms 1, 9, I'I and I9 at the critical angle corresponding to resonant response of the diaphragm.

The mechanical elements l, 9 and VI, I9 may each, or together, be provided with means for rotatably adjusting them to the desired angle 0. The rotatable adjusting means is not shown in Fig. l, since it is desired that the units of Fig. 1

be stationary. The rotatable adjusting vmeans may, however, be of the type described in the said Letters Patent 2,063,945, or as illustrated in Fig. 2. The adjusting means may comprise a manually controllable arm 2S, rigidly secured to another insulating member I3, and rotatable about a pivot I6. The unit, as a whole, may, however, be mounted in a rotatable housing (not shown) attached to the plates I3.

The diaphragms may be constituted merely of metal conducting strips. In accordance with the present invention, these strips may be electromagnetically excited as at their secured-together or inner ends by the application of radio-frequency energy directed thereupon from radiofrequency transmitters 2, in order that they may support radio-frequency energy of predetermined frequency to serve as an antenna, comprising two pairs of radio dipoles l, 9 and l'l, I9, respec tively. Conversely, the dipoles l, 9 and l1, i9 may be excited by radio waves applied thereupon from space, feeding the received radiofrequency energy supported by the dipoles to the radio-frequency receiver 2 to evidence the received radio-frequency energy. This fourelement array provides a directional radio pattern With principal maxima in the direction 4 4, at right angles to the plane of the diaphragms. A reector (not shown) may be employed behind the diaphragms, to eliminate back radiation.

Provision is thus made for simultaneously sending or receiving a sound wave along one direction 6-B, determined by the Pierce angle e, and a radio wave along another direction 4 4, transverse to the plane of the diaphragm. These directions may, under certain circumstances, be the same, as hereinafter explained in connection with Fig. 4. The radio wave will be modulated by the mechanical vibrations of the diaphragm during the transmission or reception thereby of the sound wave. The modulated radio waves may be received at a distant receiving station for demodulation by a demodulator of suitable and wellknown form, or by a diaphragm, as described herein.

The invention is thus applicable to the transmission of radio waves modulated by transmitted or received sound waves. The modulation may be effected by mechanically vibrating the diaphragms by exciting them or applying vibrational energy in response to the vibration of the magnetostrictive cores, or in response to the applying to or impinging upon the diaphragms of a sound beam received through the medium in which the diaphragms are disposed. The invention is also applicable to the reception of radio waves, as they, too, will become modulated by the Y.transmitted or received sound waves. At least four combinations of radio and sound transmission and reception are thus possible according to the present invention; namely, electromagnetic transmission and sound-wave transmission, electromagnetic transmission and sound-wave reception, electromagnetic reception and sound-wave transmission, and electromagnetic reception and sound-Wave reception.

AIf the diaphragms are constituted of vertically disposed cylindrical rods, such as the rods Ill and of Fig. 3, as an illustration, the radio Waves may be transmitted or received in all directions of azimuth, and the sound waves may be transmitted or received along conical surfaces making the critical Pierce angle 0 with the rods. An omni-directional combined radio and sound transmitter or receiver may thus be provided.

As the pluralityy of transmitters o r receivers I,

4|, 5| and 3| may obviously transmit or receive elastic vibrations at different frequencies, it is possible, according to the present invention, tok modulate the radio waves simultaneously according to different sound signals. There may be as many different modulations as there are different sound channels I, 4|, 5| and 3|. The radio-frequency transmitters or receivers 2, moreover, may provide different radio-frequency channels to` the diaphragms l, 9 and the diaphragms, 1, v|51 respectively. The invention, accordingly, provides for a multiplicity of types of secret signalling, both for transmission and reception. l,

In Fig. .4, there is illustrated an application of the present invention to use with a different type of radio-frequency and sound-vibration conductor than the elements of Figs. 1, 2 and 3, namely, the iiared truncated-cone apparatus 30`il1ustrated in Fig. 1'7 of the said Letters Patent 2,063,944, having a flare angle of /2. The truncated cone' is shown provided with a baseA disk 32, connected to an inter-converter 3, of mechanical and electromagnetic energy. This apparatus yields, by reflection from the conducting wall-surfaces vof the cone, a cylindrical parallel-sided or converging sound beam 28, parallel to the axis of the cone. This sound beam, whether produced by magnetostrictively vibrating the disc 32, or produced in response to a sound beam received by the disc 32, may be caused to modulate a radio beam transmitted or received by the cone, operating as a Wave-guide electromagnetic" horn. An antenna probe 34, positioned in the horn approximately a quarter of the radio-frequency Wave-length in front of the base disc 32, may be excited, for transmission purposes, by radio-frequency energy from a radio-frequency oscillator 2, through a radio-frequency channel 36, shown as a coaxial line. The probe 34 in the horn may servedalso for reception, in which event the member 2 would serve as a detector circuit.

The dimensions of the cone should, of course, be such as to support the particular radio frequency. AV combined directive modulated radio fre quency-and-sound-beam transmitter or receiver` is thus provided, the apparatus constituting both a directional sound transmitter or receiver and an electromagnetic horn.

Further modications will pccur to persons skilled in the art, and all such are considered to fall Within the spirit and scope of the invention.

What is claimed is:

1. An electro-acoustic system having, in combinaticn, conducting means adapted to support radio-frequency energy of predetermined frequency directed thereupon, the conducting means being transversely vibratory in response to elastic vibrations of predetermined frequency and of suflicient dimensions to produce mechanical resonance therein in response to the elastic vibrations substantially simultaneously With'the supporting of the radio-frequency energy by the conducting means, means for applying radio-frequency energy of said predetermined radio frequency to the conducting means and means `for applying transverse elastic vibrationstc the conducting means at the mechanical resonance frequency.

2. An electro-acoustic system having, in combination, conducting means adapted to support radio-frequency` energy of predetermined frequency directed thereupon, the conducting means being transversely vibratory in response' to elastic vibrations of predetermined frequency and of sufficient dimensions to produce mechanical resonance therein in response to the elastic vibrations substantially simultaneously with the supporting of the radio-frequency energy by the conducting means, means for exciting the conducting means with radio-frequency energy of said predetermined radio frequency, and means for transversely vibrating the conducting means at the me-` elements and the said transverse vibrations are.

applied to the other element provided with means for coupling the said transverse vibrations to the said one element.

4. An electro-acoustic system of the character described in claim l and in which the conducting means comprises a Wave guide.

5. An electro-acoustic system of the character described in claim 1 and in which the conducting means comprises an electromagnetic horn.

6. An electro-acoustic system having, in combination, conducting diaphragm means adapted to support radio-frequency energy of predetermined frequency directed thereupon, the diaphragm means being transversely vibratory in response to elastic vibrations of predetermined frequency and of sufficient dimensions to produce mechanical resonance therein in response to the elastic vibrations substantially simultaneously with the supporting of the radio-frequency energy by the diaphragm means, means for ap plying radio-frequency energy of said predetermined radio frequency to the diaphragm means' and means for applying transverse elastic vibrations to the diaphragm means at the mechanical resonance frequency.

7. An electro-acoustic system having, in combination, conducting means adapted to transmit or receive into or from space radio-frequency energy of predetermined frequency, means connected with the conducting means for energizing the conducting means with radio-frequency energy of the predetermined frequency to cause the conducting means to transmit the radiolfrequency energy into space or for evidencing radio-frequency energy received by the conducting means from space, the conducting means being transversely vibratory in response to elastic vvibrations of predetermined frequency and of sufficient dimensions to produce mechanical res- -onance therein in response to the elastic vibrations in order to transmit or receive the said elastic vibrations substantially simultaneously -with the transmission or reception of the radiofrequency energy by the conducting means, and

vmeans mechanically connected with the conyducting means for interconverting vibrational and electric energy at the said mechanical Yreso-f nance frequency.

8. An electro-acoustic system having, in combination, conducting means adapted to transmit -or receive into or from space radio-frequency energy of predetermined frequency, means connected with the conducting means for energizing the conducting means with radio-frequency energy of the predetermined frequency to cause the conducting means to transmit the radio-fre'- lquency energy into space or for evidencing radiofrequency energy received by the conducting means from space, the conducting means being transversely vibratory in response to elasticf'vibrations of predetermined frequency and of Ysuf- -cient dimensions to produce` mechanical resonance therein in response to the elastic vibrations 7. in order to transmitor receive the said elastic "suestanu iy'jsimultaneouslyiwan-the" mission or' recept n' of' theradio-frequency Jblyfth'e end' meansjand'me'ans con'- n tlng ythe :conduc'tlng means" with means for anplying mechanical"tansvrse'vibrauons of the saidA resonancemfrequency' to the "conducting In nsorV for,evidencing`"'tl1e mechanical trans- .s vibratie'ns'lof.y the said' resonance frequency received. byftheeonducting ineansl" 9,An electr'oracoustic system of the character described infclairr'iv and injyhich'the conducting fielsccmprisesa diaphragm; s

1t ,A Aiielect l acustic' system of the character described in claim Sand in 'whi'c'hthe conducting means comprises avrai/e guide.

L :Y electro-acoustic'system of the character described in claiml and iriv'rhich the -conc'ucting means, comprises an electromagnetic horn.

" Y1 2 An electro-acousticsystem'of the character desc ibed in clairndand inwhich 'the conducting me' nsfcomprises'a conicarelectromagneti'c horn disposable 'in mediumuvithdts axis substantialyparallel tothe'direction of transmission or reception of the said elastic rkVibrati'ns and having flared Walls disposable at an 'angle to the said direction such that'the'said transverse elastic ations therein shallm'have a velocity component, in` thesaid direction',- substantially equal to theyelolcity'of the'said elastic Vibrations in the m. 1,3, Anelectro-acoustic system of the character described claim 8 and'in which the `conducting angularly disposable in a medium at an angle e the. direction of transmission or reception of the said elastic vibratioisin Ythe medium such that thetransverse elastic lvibrations in the conducting means havel a velocity 'component along th fsaid direction substantially'equal to the veloc- 'of the elastic vibratins in the medium.

` le.' iny electro-alc'dsfti` system of the character described in claim 3 andinV which the conducting means adapted omni-directionally to transmit (if, Iceivethre said radofrequen'cy energy.'

l5, An'electro-acoustic system havinggin combination, conducting means adapted to transmit into' space radio-frequency energy Vof predetermined frequency, means connected with the conducting means for"`energizing the conducting means with radio-frequency energy of the pre'- dete'rmined f re'zquencyy to cause the conducting means'to transmit `the radio-frequency energy into "space,` the conducting' means' Vbeing transversely 'vibratory res'pbnse to elastic Vibrations of predetermined frequency'and of sufcient dimens ins to produce mechanical resonance therein in"respon`se to the'elastic vibrations in order to transmit or receive the said elastic Vibrations substantially simultaneously with the transmission of the radio-frequency energy by the conducting means, and means connecting the conducting means with means for applying mechanical transverse vibrations"of"the said resonance frequency lto 'the conducting means lor for evidencing ythe mechanical transverse vibrations of the said resonance frequency received'b'y the conducting means.

1'6. An electro-acoustic system having, in combination,I conducting means adapted to receive from space radio-frequency energy of predetertres.

rnir'ied"frequency',l means connected'with the con- .iibieieirie .repense i0 @lesbie vibratie@ 0f predetermined frequency and of sufficient dimensions to produce. mechanical resonance therein in response to. the"elasticivibrations in Vorder tg transmit or 'receive the'said elastic vibrations substantially. simultaneously with the reception:

of the radio-frequencyenergy by the conducting means, and means connecting the conducting means With means for applying mechanicaltransverse vibrations 'ofthe said resonancefrequency tothe conducting means or"for evidencing the mechanical transverse'vibrations ofthe saidresonance frequency received by the conducting means. f

17. An electro-acoustic system having, in combination, a plurality of. conducting elements adaptddirectionally vto transmit' or receive into or from space radio-frequency energy of predetermined frequency, means connected. with the conducting elements for energizing the conducting'elements `W`ith radio-frequency' energyv off the predetermined frequency to cause the conducting elementsto transmitr the radio-frequency -energy irit spaceor'for evidencing 'radio-frequency en'- e'rgy received by the conducting elements from spacefthe conducting elements being 'transversely vibratory in responseto elastic vibrations'of predetermined frequency and of sufficient 'dimensions' Yto produce mechanical resonance therein in response'to"the"elastic `vibrations'in order to transrni'torreceive thes aid elastic vibrations sub'- stantially Asimultaneously KA'Wi'h 'the transmission or reception'of'the radio-'frequency energy by the conductingelementsg` a'nd means connectingl the conducting elements 'with'means for applying mechanical'transversevibrations of the said resonance frequencyto the'conduciing elements or for evidencing the'mechanical transverse vibrations of the'said resonance frequency received by the' conducting elements.

18. An electro-'acoustic system of the character described 'in 'claim`17 and in which the plurality of conducting Yelements are respectively energized by or respectively receive a 'plurality of different predetermined radio 'frequencies and are transversely vibratory at' the same mechanical resonance frequency.

' 19. An electro-acoustic system of the character described in claim' 17 and in'which the 'plurality of conducting elements are'energized by or receive the same predetermined radio frequency and are respectively transversely vibrator'y ata plurality of diernt mechanical resonance frequencles.

20. An electro-acoustic system of the character described in claim 17 and in which the plurality of conducting' elements are respectively energized by or respectively receive a plurality of different predetermined radio frequencies and are respectively transversely vibratory at a plurality of different mechanical resonance frequencies'.

21. An electro-acoustic system having, in combination, a plurality of electrically and mechanically isolated conducting elements adapted directionally to transmit or receive into or from space radio-frequency energy of predetermined frequency, means connected with the conducting elements for energizing the conducting means with radio-frequency energy cf the predetermined frequency to clause the conducting elements' directionally to transmit the radio-frequency energy'into space or. for evidencing radio-frequency energy directionally received bythe conducting elements from space, the conducting elements being transversely vibratory in response to elastic vibrations of predetermined frequency and of sufficient dimensions to produce mechanical resonance therein in response to the elastic vibrations in order to transmit or receive the said elastic vibrations substantially simultaneously with the directional transmission or reception of the radio-frequency energy by the conducting elements, and means connecting the conducting elements with means for applying mechanical transverse vibrations of the said resonance frequency to the conducting elements or for evidencing the mechanical transverse vibrations of the said resonance frequency received by the conducting elements.

22. An electro-acoustic system having, in combination, conducting means adapted *o support radio-frequency energy of predetermined frequency directed thereupon, the conducting means being transversely vibratory in response to elastic vibrations of predetermined frequency and of suiicient dimensions to produce mechanical resonance therein in response to the elastic vibrations substantially simultaneously with the supporting of the radio-frequency energy by the conducting means, means for applying radio-frequency energy of said predetermined radio frequency to the conducting means, means for applying transverse elastic vibrations to the conducting means at the mechanical resonance frequency, and vibration-absorbing means at a boundary of the conducting means to damp the vibrational energy at the said boundary.

23. An electro-acoustic system having, in combination, a plurality of conducting elements adapted directionally to transmit or receive radiofrequency energy of predetermined frequency directed thereupon, the elements being transversely i vibratory in response to elastic vibrations of predetermined frequency and of sufficient dimensions to produce mechanical resonance therein in response to the elastic vibrations substantially sil0 multaneously with the directional transmission or reception of the radio-frequency energy by the conducting elements, means for applying radiofrequency energy of said predetermined radio frequency to the conducting elements and means for applying transverse elastic Vibrations to the conducting elements at the mechanical resonance frequency.

ROBERT HARVEY RINES.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,763,220 Chromy June 10, 1930 2,061,699 Fox Nov. 24, 1936 2.063,946 Pierce Dec. 15, 1936 2,402,459 Smith June 18, 1946 2,406,111 Sheeld Aug. 20, 1946 2,407,328 Turner Sept. 10, 1946 2,412,631 Rice Dec. 17, 1946 2,415,407 Benioff Feb. 11, 1947 2,421,263 Herbst May 27, 1947 2,431,018 Bailey et al Nov. 18, 1947 2,434,926 Hayes Jan. 27, 1948 2,437,270 Peek Mar. 9, 1948 2,444,967 Turner July 13, 1948 2,448,713 Hansell Sept. 7, 1948 2,448,787 Ferrel Sept. 7, 1948 2,461,005 Southworth Feb. 9, 1949 FOREIGN PATENTS Number Country Date 335,125 Italy Feb. 1, 1936 596,439 Germany May 3, 1934 694,523 Germany Aug. 2, 1940 344,523 Great Britain Mar. l2, 1931 

